Gents this, as stated in the video, is not a definitive answer to why this happens. Its all just a theory. The bigger part of this is that it hopefully helps someone whos struggling with cold bore already. I encourage everyone to give it a shot and report back here. It has worked for me and several others but thats not a guarantee it would work for you, id be interested in hearing if it did or didnt help you here in the comments!

Great video man that’s insane how easily that works

Theirs many factors that cause cold bore. Up till now, 2K+ rifles built. It's primarily due to tight spots in a barrel. Hence why I have an air gauge tool. Not sure about the moisture, but I see cold bore even here in Arizona. Great thing about this community is we can gather all data together and conclude a fix

Finally the condom i been carrying for years for when I get lucky got used. Thank you

This is awesome! Thank you for sharing.

Dude this is the most important video I’ve watched this year!!! Wow - thanks so much brother 🙌🏻🙌🏻🙌🏻🙌🏻

Thanks Josh and super easy solution

I really enjoy your videos. I have learned a lot. Thanks

That is really cool!! I’m looking forward to seeing the future tests! Great work,

Thanks, great video!

Great video. I learn something every time I watch your videos. Keep it up!!

Great info. I’ll be checking this out the next time at the range.

Love me some scientific method! Thanks for moving the knowledge limit forward on this issue.

Interesting. Thanks for the info

Love the video man, great work!

Great idea from the guy that told you this. I’ll try it for myself and see.

Thank you 😊

Wow, that’s an awesome find! Glad to know what actually causes that cold bore shot difference.

That was pretty cool. Good info

Another great vid. Happy New Year mate.

This may be the nugget of info I've been looking for to do better in the Rabbit Hole of 22 bench. Since I shoot a bimonthly bench match with ranges from 75-250, This will be a hard secret to keep if it works and besides I know a bunch of my friends that shoot it also are followers of your channel. Have a great New Years and keep the juice flowing.

Thx for the information. got supersonic bang on every first shot and never knew why. Greetings from germany

A while back I had a hunch that its not the temperature but the atmospheric conditions in the barrel that cause the first flyer, thanks for confirming my suspicions, people didn't believe me cause I worded it poorly.

About 25 years ago the long range blackpowder cartridge rifle shooters in Canada found that a puff of breath through a rubber tube into the chamber after each shot improved accuracy. They were shooting duplex black over smokeless loads in 45/90s and 45/100s. In alternating shots there was just enough time to reflexively put that step in the firing point routine while the other shooter got off his shot.

Great video! I’ve seen the same thing when testing SK and Eley. About 30-40 fps cold bore. You can hear it down the line at a match too if you’re paying attention to other shooters. I’ve been noticing this for a while now. I’m going to try out these tips 👍🏻

Excellent video

Very interesting Josh, seems like your on to it. I never would have thought this was the cause . The results don’t lie. Thanks mate

And this video is exactly why I follow you! Very cool!

Who'da thunk it! Excellent info Josh! Appreciate you!👍

Wow, great video, thanks for info.👍

Amazing, mystery solved i think! cant wait for the follow up video. cheers...

Thanks for sharing

That’s exactly what I was thinking.. that the more oily type lubes are thinner and when cooled off won’t be as think in turn causing less back pressure 🤷🏻‍♂️ I’m excited to see the test results but it definitely makes sense that eley an others with thicker wax type when cooled will be thicker. Thanks for the info great content as always!!

thanks Josh, again great informative video, thank's for sharing the insight to cold bore, i've often wondered what makes this issue...my Ruger American in 22lr suffers from cold bore, second and subsequent shots are all clover leaf groupings on POA...quite annoying in hunting situations, i just make sure a fouling round is fired first soon before going hunting, where POI is so so important...

Thanks Josh I will try to keep that info in my old mind at my next match.

Hey Josh, I use Eley Match, SK Standard Plus, and CCI Standard Target. All ammo dose the cold bore shot in my rifles. Have seen that cleaning the bore lessens the effect of the cold bore shot. I am going to try blowing my breath down the bore using a short piece of small diameter clear vinyl tube that is available from most hardware stores. As it's not going to do any harm, and well worth a try.

Awesome Video KYL Killa!! I have witnessed this work very well.

Interesting stuff!

Very interesting. I'll try the "blowing trick" visiting next time the range. Thanks for the video.

And great informative video !!!👍

Josh great videos, enjoy every single one, very informative and well done, thanks for your hard work. I tried the straw trick on my FX Impact M3 22 cal. for 3 days, it worked, cold bore shift disappeared. I'm adding a straw to my shooting tools from now on.

Fascinating stuff 🤔👍

This is pretty interesting gonna have to test this

Josh that’s awesome man super cool you shared this now I have to try it out. Thanks and another great video.

I usually just run a dry bore mop/swab down the bbl to clean things out. I do let the bbl cool some before the next group/chrono run. Works well for me but my firearms are nowhere near the league yours are in. Thanks for all your informative videos.

Very interesting good information.

Good one !

this is great info. my factory cz457 has a heck of a cold bore shift using eley ammo. will have to try this hack at the next match.

Super interesting. Time to pull out the chrono and do some testing on my end!

sick scope

I've read this theory in forums, but never saw this vid. A couple things I note - 1) for your straw, maybe cut the 'short' end a bit so it fits in the chamber area easily. That would let you be 5-6 inches farther away from the rifle - not look as 'intent'. 2) Can you test this effect with just 'dry air' like with a fan and hose? to eliminate the moisture for comparison. I haven't watched Part 2 yet so maybe these have been addressed ?

I was always under the impression it was caused by a carbon ring. And once you fired that first shot, the carbon ring warmed up and kind of normalized. Learn something new every day!

Very informative and interesting video, thanks for sharing!

Wow this is crazy!

Good information

Go to a black powder cartridge match, you blow thru after firing a round for the moisture, fouling. Cool that it works on rimfire

That's awesome! And super easy

Very interesting video. I have to admit I always thought it was a temperature thing.

Wow. Great presentation, Bro. You look as good as anyone, blowing your barrel. Well, I can think of some ladies who would look better doing it. But this was very informative. We have never known, definitively, what causes cold bore shift. We now have a clearer picture.

I hope you get it figured out man. Glad my rifles are well tuned and they don't exhibit this.

Several years ago Bill Calfee wrote about moisture in the barrel and how it relates to cold bore. I'm pretty sure the article's in his book The Art of Rimfire Accuracy

Excellent video! Great theory and supporting evidence. I'm going to research and work on this. I'll let you know if I come with anything.

Great video. Would have liked to see the accuracy added. Thanks for informative videos.

Back in the day doing biathalon, never thought about the cap on the bore keeping this down. Just never had a problem with that rifle compared to my hunting rifle. Interesting, to be sure.

Good sir

Great video! Man I’m glad there are nerds like you doing this stuff so nerds like me can learn from you! Seriously though, I think this nailed it, also brings to mind what Kenny from DPG has said about barrels that have high spots introducing friction requiring more lube/ moisture to overcome the cold bore shot. I suppose starting with the truest barrel possible can minimize if not eliminate cold bore velocity deviation, and of course shooting ammo with lowest standard deviation and extreme spread, ie ammo that is lot tested for your barrel greatly smooth things out. The Pursuit continues! Curious if you took any sniper courses in the Army?

I HATE THAT FIRST SHOT ..I will 100% be giving this a try !!.I have a couple 10/22's I built ..I love all your videos !!.. thank you !!!...

This reminded me that big naval guns have used compressed air to blow out the remaining gases after a shot...this probably allows them to get maximum, and stable, muzzle velocity...ive been thinking about a system to clear gases from the barrel of a rifle, between shots...it's tricky, but i think can be done mechanically, and with a, let's say, manual air source...of course, the whole thing ccould be done electrically, but maybe it's sub-optimal to need a battery. Imagine, not just no 'cold bore' issue, but overall more stable velocity, and accuracy. As someone more known than i would say: it's just a thought

I have a cold bore shift on my .243 wonder if this would work on that ? Very interesting well done 👍

Wow!!!

Odd, I would have thought pre warming a barrel with a fan might help eliminate a cold bore shot and using a fan between rounds, you basically proved exactly the opposite. Also, standing a rifle straight up on a rack lends to faster barrel cooling, so maybe keeping a barrel level and capping both ends as you have shown might prevent cold bore shift. Thanks for the video brother.

Who'd a thunk it? Great video.

Shane B at Lapua Ohio demonstrated cold bore shifts (and complete control thereof) with a very short down time (time to reload magazine). He combats it by keeping spent round in chamber and bolt closed while reloading mag for next lot test. This prevents the environmental filter vacuum positioned right above the action from sucking air through the bore and out the action. This leads me to believe that controlling the oxygen in the barrel as opposed to the moisture content may be the key. Much like suppressor first round pop. Obviously keeping the action closed with a spent case inside is not feasible at a match, but the H&S ECI's and something over the muzzle (cot, plug, masking tape, etc) is. I appreciate your efforts and look forward to the next round of testing. I also appreciate a pro like GS sharing his own research.

Great video josh. Have always wondered about this. I would like to see if the finger glove method works overnight.

Marginal gains moves us forward, excellent video. Maybe just use a 2nd chamber empty flag in the muzzle instead of the rubber glove, easy to see its there.

Josh I absolutely love these data gathering video's I call them. Though this one will cause me much grief. First off a good friend of mine told me 20 yeas ago put a foam ear plug in the end of the barrel when you are done shooting and I thought he was bat crap crazy. Dude do you mean to tell me I need to call this dude and tell him he was RIGHT? I think I would rather go on a 20mile hump with my 70pound alice pack in shorts in South Korea winter. The other thing that makes this video great outside of the nice new room yes I am still drooling over it is the fact of how ridiculous you looked blowing on that straw LOL. You surely deserve for this video to go viral super educational and FUNNY to watch.

Didn’t look bad but you got to do what you need to do to make it work.

Very interesting Thanks for sharing! So cold bore first shot give er a blow 30 rounds walk down then back at bench .Does it need another blow say 10 min.between.

Blowing into the bore to maintain consistency and accuracy is a common step with Blackpowder cartridge shooters. Next time, consider shooting at paper at 100yds to 200yds to see if the 'cold bore' shot also changes POI. Varying velocities alone doesn't indicate the that POI will also change ... at least enough to be a problem.

My CZ457 MTR definitely has cold bore…. About 2” high and little left at 100yds. I will test with a longer piece of 1/4” vinyl tubing and report back.

I'm so glad you posted this video because I've been peeing in my barrels for years and getting some really strange looks. If you think that blowing through a straw works, you should try peeing. More moisture, better results.👌

Some food for thought.!🤔 After the straw and or the finger cot was there a point of impact shift like the cold bore? If not you could be on too something.

What !?? I'm sure gona try this

In my cz457, just the time it took to reload a 10rd magazine would be long enough for the cold bore shift. The idea that it is moisture related was brilliant. I replaced the factory barrel with a Lilja barrel. Mainly because I wasn't happy with the overall grouping I was getting. I will have to keep an eye out for the cold bore shift on the first round. Great video!

One thing I was wondering with the straw is there is moisture in your breath. I was kind of surprised at the result. There might be another reason why this works and your summation might be wrong but the result works anyway.

Way cool, Josh. Another great video. I wonder if you could just exhale on the first round or potentially use a damp rag on the projectile?

Interesting. I'm also curious to see the effect on accuracy if the finger cot is left on the barrel by accident.

Wonder if this is the same as first round pop with suppressors, where you have higher oxygen % in the barrel and suppressor, and that first round ignites it. But that is interesting and a simple fix.

Use electrical tape. A lot of hunters use black electrical tape over the muzzle to keep rain out of the barrel. When shooting, the gasses that escape around the bullet, blow the tape off before the bullet exits, so the bullet doesn't hit the tap when fired.

It would be jnteresting to shoot the finger condom thing off the end of the barrel on the first shot and see if the round is significantly affected by going through it. You can tape up a muzzle brake on a centerfire completely and not affect the first round. See Jon Pynchs video.

How does this relate to a carbon ring, if at all? Great vid.

Excellent bit of information. I’ll test it out here in Ireland 🇮🇪 Will you show what the cold bore is on paper as well. Would make more sense to see the group also 👌💪🇮🇪🍀

Those little finger doohickies were on a few rifles at teh Worlds champs in Italy. I'm betting thats where Greg got started on this. I dismissed it as nonsense but good to hear it may have validity!

it's theory but worth testing, this makes me wonder if lubed ammunition has less cold poi shift when compared to raw lead bullets, if you blow breathe down the chamber with a straw it should make a difference in velocity, i will test with a chronograph the difference between dry patch pass and breath fogging

Yep, moisture, traces of cleaning solution. It's the law of physics - when metal is cooling - it's shrinking when heating - it is expanding. If it's shrinking - the force of resistance growing - the bullet loses more energy in the barrel. Ideally, it should be a thick barrel preheated to normal operational temperature and sealed. As soon as we get ideal ammo - we can start to worry about that. For now, the quality of relatively affordable ammo is the bottleneck.

Josh, I appreciate the scientific approach that you employ to test your hypothesis. Your experimentation and resulting data are interesting, and perhaps compelling, but not necessarily conclusive. I'm not 100% convinced that the cold-bore velocity shift is 'caused' by 'moisture', because moisture was not measured. If moisture causes a decrease in velocity, then the removal of moisture in a warm (hydrated) bore should cause an increase in velocity similar to the cold-bore shot. This was not tested. Since there are several potential contributors to the observed shift in velocity, then a "Design Of Experiments" (DOE) is needed to isolate the predominate cause and characterize the resulting effect. Is it possible that the bullet lubrication is affected by temperature in a way that we do not understand? What about chamber temperature affecting case expansion/sealing? I'm looking forward to learning, along with you and your other devoted channel-watchers as you pursue this gremlin of accuracy. Thanks for all you do for our community.

I wonder if that would work for my m96 , which is a 6.5x55 cartridge. It has a terrible cold bore shot, but after that it's just over .33 MOA. I'll have to try it. Thanks for the research.

Can't believe this this is great.. do you think running a dry patch through the barrel

Happy New Year Birthday To Me, Pursuit of Accuracy.

If this small amount of water vapor can affect lubrication / speed of bullet, then I wonder how much the remaining smoke in the barrel could also change speed .